Pressure responsive snap acting switch



June 2, 1964 BEEMAN 3,135,844

PRESSURE RESPONSIVE SNAP ACTING SWITCH Filed Sept. 20, 1962 2 Sheets- Sheet 1 INVENTOR.

LYLE BEEMAN BY I ATTORNEYS United States Patent 3,135,844 PRESSURE RESPONSIVE SNAP ACTING SWITCH Lyle Beeman, 738 Barrington, Grosse Pointe Park 30, Mich. Filed Sept. 20, 1962, Ser. No. 225,004

21 Claims. (Cl. 200-83) This invention relates to switches and particularly to switches Which'are responsive to fluid pressure to make and break electrical connections, such as shown in my prior Patents 2,754,388, 2,791,658 and 3,042,770.

It is an object of the invention to provide a pressure switch of an improved construction.

It is a further object of the invention to provide such a pressure switch which is efficient, reliable, utilizes a minimum number of parts and is low in cost.

It is a further object of the invention to provide such a pressure switch which has a novel snap acting spring assembly.

It is a further object of the invention to provide such a pressure switch wherein the snap acting spring assembly is powerful and has long life.

It is a further object of the invention to provide a pressure switch having a novel means for setting the switch to operate automatically, manually or in the olf position.

In the drawings:

FIG. 1 is a side elevation of a pressure switch embodying the invention.

FIG. 2 is a plan View of the same.

FIG. 3 is a sectional view taken along the line 3-3 in FIG. 1.

FIG. 4 is a sectional view taken along the line 44 in FIG. 2.

FIG. 5 is a sectional view taken along the line 55 in- FIG. 2. 7

FIG. 6 is a perspective view of the snap action'spring assembly used in the pressure switch.

FIG. '7 is a sectional view on an enlarged scale taken along the line 77 in FIG. 2. Y

FIG. 8 is a sectional view onan enlarged scale'taken along the line 88 in FIG. 2.

FIG. '9 is an exploded side elevation "of a portion of the control means for the pressure switch.

I Referring to FIG. 1, the pressure switch embodying the invention comprises a casing having a base 21 and spaced side walls 22,23. A U-shaped cover 24 is placed over the casingand includes peripheral flanges 25 which extend inwardlyinto contact with the outer surfaces of the walls 22, 23. Walls 22, 23 have conduit sections 26,

27 connected thereto through which electrical wires are A threaded.

As shown FIGS. 5 and 5, an inverted'U-shaped bracket 28 is mounted on the bottom wall 21 in spaced relation thereto by screws 29. Screws 29 also support an enclosure 30 and a diaphragm 31 adjacent the bottom wall 21 defining a chamber 32 which communicates through a conduit 33' with-a source of pressure (not shown). The portion of bottom wall 21 above the diaphragm 31 is bent upwardly and spaced therefrom.

A U-shaped actuator 34 rests on the diaphragm and has legs 35 thereof extending upwardly through slots-36 in the bottom wall 21. a

The movement of the diaphragm 31 due to pressure in the chamber 32 istransmitted through the actuator 34 to a snap action assembly 40( FIG. 6). The snap-action assembly 40 includes a spring support 41 made of sheet metal and having one end thereof bent upwardly to form 'a hook 42 that extends through a slot 42min a flange 42b bent upwardly from the bottom wall 21 (FIGS. 3, 5, 7). eludes longitudinally extending side flanges 41a. A sinu- The spring support 41 is generally fiat and in- "ice ous booster spring 43 is mounted on the spring support 41. As shown in FIGS. 6 and 7, one end of the sinuous booster spring 43 extends as at 44 below an upwardly struck tab 45 on the spring support and the other end thereof is clamped between the spring support 41 and a follower 46 which is yieldingly urged downwardly by a spring 47.

As shown in FIGS. 4 and 7, a pin 48 extends upwardly through the bottom wall 21 through the spring 47 and an adjustable nut 49 is threaded on the upper end of the pin 48 to vary the tension on the spring 47. A spring follower 50 is interposed between the upper end of the spring and the nut 49.

As further shown in FIGS. 6 and 7, a substantially flat leaf spring 51 has the ends thereof reduced in cross section as at 52 and fitting into slots 53 in the endmost undulations of the sinuous spring 43 so that the spring 51 is compressed lengthwise and thereby bowed. As shown in FIGS. 8 and 6, the booster spring 43 has the central portion thereof cut away to define two sinuous sidels strips 43a, between which the leaf spring 51 exten s.

Referring to FIGS. 4, 5 and 8, a switch block 55 of insulating material is mounted on the U-shaped bracket 28 by screws 56, 57. Screw 56 extends upwardly through an opening in the bracket 28 and a sheet metal nut 58 is threaded on the upper end thereof. Screw 57 similarly extends through the U-shaped bracket and a sheet metal retainer element 59 is threaded into the upper end thereof. As shown in FIG. 5, connector terminals 60 are provided on the upper surface ofthe block and wire connections can be made to these terminals by screws 61. Each terminal 60 includes an L-shaped portion 62 extending downwardly therefrom and connected thereto as by riveting at 63. Each L-shaped portion 62 extends below the underside of the central portion'64 of the block 55. A U-shaped contact spring 65 extends from one of the elements 62 toward the other and contact buttons 66 are adapted to complete a. circuit from one to the other.

The contact springs 65 are moved into and out of switch closing position by a thrust member 70 of insulating material which, as shown in FIG. 7, includes a notch '71 that extends through a slot 72 in the leaf spring 51 (FIG. 6) and engages the leaf spring 51 so that vertical reciprocation of the thrust member 70 is produced by flexing of the leaf spring 51 in opposite directions.

The magnitude of the force exerted by the spring 47 is varied by setting the nut 49 inwardly or outwardly on the post 48. Means are provided for varying the pressure at which the switch will close and comprises a leaf spring 73 which has one end 74 thereof engaging the underside of the spring support 41 and the other end 78 thereof engaged by a lighter weight helical spring 75 on post '76, the tension of which is adjusted by a nut 77 threaded on post 76. The centralportion of the spring 73 engages the top surface of wall 21 of the casing. The other end 78 of the leaf spring 73 is bent downwardly and engages'the bottom wall 21 of the casing as the spring support 41 moves upwardly to limit the extent during wardly through an opening in the top-wall of the cover 24 (FIGS. 7, 8). The knob 80 is supported in a hollow projection 82 of the block 55 which extends upwardly through the opening'in the cover 24 and is yieldingly held in relation thereto by a sinuous spring element 83 which extends upwardly into the central hollow portion of the hub 81 and has an arm that extends upwardly into frictional engagement with the interior surface of the.

hollow projection 82. A sheetmetal sleeve 84 is telescoped tightly over the hub 81. The sleeve includes a semi-circular horizontal slot 35 adjacent the upper end thereof and a helical slot 36 adjacent the lower end there of (FIG. 9). The upper end of the retainer 59, heretofore mentioned and shown in FIGS. 8 and 9, engages the upper slot 85 to hold the sleeve 84 and, in turn, the knob 80 in assembed relation. An L-shaped metal member 87 is provided between the sleeve 84 and the retainer 59 and includes an upper projection 38 that extends into the helical slot 86. The lower horizontal leg 89 of the L-shaped member 87 extends into an opening 90 in the actuator 70.

When the knob 80 is rotated to one extreme position, clockwise as viewed in FIG. 2, the sleeve 84 is-rotated and in turn, moves the L-shaped actuator 87 tothe top of the helical slot holding the thrust member 70 upwardly and retaining the leaf spring 51 in upwardly bowed position. In this position, the switch contacts are held closed. Similarly, when the knob is turned to the opposite extreme position, the projection 88 on the L shaped member 87 is moved to the bottom of the helical slot 86 holding the thrust member 70 in its lowermost position and holding the leaf spring 51 in downwardly bowed position with the switch contacts open.

In the intermediate position of the knob 8b, the actuator 87 is positioned adjacent to the middle of the helical slot with arm 89 in such position relative to slot 90 that the actuator 70 is free to move in either direction, up or 7 down, under the action of pressure;

, The operation of the pressure switch in the automatic tacts 66 are closed, the ends of the leaf spring 51 are bowed downwardly thereby urging the thrust member 70 upwardly. When the fluid pressure reaches a predetermined amount, diaphragm 31 is flexed upwardly causing the actuator 35 to move upwardly and flex the leaf spring by swinging the spring support 41 upwardly. v The leaf spring is thereby caused to flex until it passes a center position after which it will be bowed with its ends upwardly and its center downwardly by a snap action.

position wherein the switch contacts 66 are open. As the pressure in the fluid line 33 decreases, the dia- 'phragm 31 will'move downwardly permitting the actuator '34 to move downwardly under the action of the spring 47. This movement will initially be independent of the position of the spring 75 until the spring support 41 con tacts the end 74'of the spring 73. When the spring support contacts the free end 74 of the spring 73, the spring 47 actingthrough the spring support must overcome the action ofthe spring 73 beforethespring support can move downwardly sufliciently to permit the leaf spring 51 to flex by a snap action to its originally bowed position. Because of this, the pressure at which the switch contacts will close depends upon the force exerted by the spring 73. This can be adjusted by turning nut 77. 0n

the up stroke, the effectiveness of the spring 73 is limited by the stop 78 which limitsthe extent of the action of the spring so that the movement of the spring support 41 is thereafter opposedonly by, spring 4'7.

I claim:

' 1. Ina pressure switch, the combination comprising a casing,

This will move the thrust member 70 downwardly .to a 1 a rigid spring support member pivoted at one end to said casing about an axis with its other end free, 'a booster spring mounted on said spring support, a snap-action leaf spring having the ends thereof mounted on longitudinally spaced points on said booster spring such that the leaf spring is longitudinally compressed and bowed,

pressure responsive means operable on said spring support to pivot said support,

switch means, l

means operatively connected to the leaf spring and the switch means and responsive to the snap action movement thereof caused by pivotal movement of said spring support,

and means operable on said last-mentionedmeans for selectively positioning said last-mentioned means in such a manner that the leaf spring is permited to flex, is held in one bowed position, and held in the opposite bowed position.

2. The combination set forth in claim 1' including means for applying an adjustable yielding force to said free end of said spring support.

3. The combination set forth in claim 1 including means for applying a yielding force in opposition to said firstrnentioned yielding force during a portion only of the travel of the free end of the spring support. 4. A combination set forth in claim 3 wherein said lastmentioned means comprises a single leaf spring having one end thereof engaging said spring support and an intermediate portion thereof engaging said casing.

5. The combination set forth in claim 4 wherein the other end of said last-mentioned leaf spring is adapted to engage the casing and limit the movement of the other end of said leaf spring.

6. The combination set forth in claim 1 wherein positioning means comprises 7 a rotatable member on said casing, a thrust member operatively connected to said leaf spring,

a connecting member interconnecting said rotatable member and said thrust member,

and a helix on said rotatable member engaged by said connecting member whereby when said rotatable member is rotated, said connecting member is caused to move axially relative to said rotatable member'and move said thrust member,

-, said rotatable member at one extreme position holding the thrust member and, in turn, the leaf spring in one bowed position, at its opposed extreme position hold 8. The combination set forth in claim 7 including a switch block in which said switch means is positioned,

a screw for supporting said block on said casing, and a retainer held in position by said screw,

said retainer holding said sleeve in axial position on saidhub by engagement therewith.

9. In a pressure switch, the combination comprising a casing, a I

a rigid spring support member pivoted port,

mounted on longitudinally spaced'points on said booster spring such that the leaf spring is longitudinally compressed and bowed,

a pressure responsive means operable on an intermediate portion of said spring support,

switchmeans, j 1

means operatively'connected to the leaf spring and the switch means and responsive to the snap action move ment thereof, a

said

at one end to said casing about an axis with its other end free, a sinuous booster spring mounted on said spring supa snap-action leaf spring having the ends thereof 3 and means operative on said last-mentioned means for selectively positioning said last-mentioned means in such a manner that the leaf spring is permitted to flex,

is held in one position, and held in the opposite bowed position.

10. In a pressure switch, the combination comprising a casing,

a rigid spring support member pivoted at one end tc said casing about an axis and the other end being free,

a sinuous booster spring mounted on said spring support,

a snap-action leaf spring having the ends thereof mounted on longitudinally spaced points on said booster spring such that the leaf spring is longitudinally compressed and bowed,

said booster spring having an intermediate portion thereof cut away to define'two sinuous strips between which the leaf spring flexes,

pressure responsive means operable on an intermediate portion of saidspring support,

switch means, 7

means operatively connected to the leaf spring and the switch means and responsive to the snap action move ment thereof,

and means operative on said last-mentioned means for selectively positioning said last-mentioned means in such amanner .that the leaf spring is permitted to flex, is held in one position, and held in the opposite bowed position.

11.- In a pressure switch/the combination comprising a casing,

a rigid spring support member,

said casing having a slot therein,

said spring support having one end thereof turned upwardly through said slot to pivot said spring support to said casing,

a sinuous booster spring mounted on said spring supa snap-action leaf spring having the ends thereof mounted on longitudinally spaced points on said booster spring such that the leaf spring is longitudinally compressed and bowed,

a pressure responsive means operable on an intermediate portion of said spring support,

switch means,

a thrust member operatively connecting said leaf spring to said switch means and responsive to the snap-action movement thereof,

means operative on said last-mentioned means for selectively positioning said last-mentioned means in such a manner that the leaf spring is permitted to flex, is held in one position, and held inthe opposite bowed position,

spring means acting on said spring support in opposition to said pressure responsive means,

and spring means acting on said spring support in the same direction as said pressure responsive mean during a portion only of the pivotal movement of said spring support.

12. In a pressure switch, the combination comprising a casing,

a rigid spring support member,

said casing having a slot therein,

said spring support having one end thereof turned upwardly through said slot to pivotsaid spring support to said casing,

a sinuous booster spring mounted on said spring supa snap-action leaf spring having the ends thereof mounted on longitudinally spaced points on said booster spring such that the leaf spring is longitudinally compressed and bowed,

pressure responsive means operable on an intermediate portion of said spring support to flex the same and thereby cause the same to snap into a reversely bowed position,

switch means,

a thrust member operatively connecting said leaf spring to said switch means and responsive to the snapaction movement thereof,

spring means acting on said spring support in opposition to said pressure responsive means,

and spring means acting on said spring support in the same direction as said pressure responsive means during a portion only of the pivotal movement of said spring support.

13. The combination'set forth in claim 12 wherein said 14. The combination set forth in claim 13 wherein the other end of said last-mentioned leaf spring is adapted to engage the casing and limit the movement of said leaf spring.

15. Thecombination set forth in claim 12 wherein said positioning means comprises a rotatable member on said casing,

a hook member interconnecting said rotatable member "and said thrust member,

means for retaining said hook member in engagement with said rotatable-member,

and a helix on said rotatable member engaged by said hook member whereby when said rotatable member is rotated, said hook member is caused to move axially relative to said rotatable member and move said thrust member,

said rotatable member at one extreme position holding the thrust member and, in turn, the, leaf spring in one bowed position, at its opposed extreme position holding the thrust member and, in turn, the leaf spring in the oppositely bowed position and in its intermediate position permitting the leaf spring to bow in either direction.

16. The combination set forth in claim 15 wherein said rotatable member includes a hub,

switch block in which said switch means is positioned,

a screw for supporting said block on said casing and a retainer held in position by said screw,

said retainer holding said sleeve in axial position on said hub by engagement therewith.

18. In a pressure switch, the combination comprising a rigid spring support member adapted to be pivoted at one end of a casing,

a sinuous booster spring mounted on said spring support,

a snap-action leaf spring having the ends thereof mounted on longitudinally spaced points on said booster spring such that the leaf spring is longitudinally compressed and bowed.

19. In a pressure switch, the combination comprising a casing,

a rigid spring support member adapted to be pivoted at one end of said casing about an axis and the other end being free,

a sinuous booster spring mounted on said spring support,

a snap-action leaf spring having the ends thereof mounted on longitudinally spaced points onsaid booster spring such that the leaf spring is longitudinally compressure responsive means operable to flex said leaf spring and thereby cause the'same to snap into a reversely bowed position, I

switch means, I

a thrust member operatively connected to the leaf spring and the switch means and responsive to the snap action movement of said leaf spring,

means operative on said thrust member for selectively positioning said thrust member in such a manner that the leaf spring is permitted to flex, is held in one position, and held in the opposite bowed position comprising a rotatable member on said casing,

a hook member interconnecting said rotatable member and said thrust member,

means for retaining said hook member in engagement with said rotatable member,

7 and a helix 'on said rotatable member engaged by said hook member whereby when said rotatable member is rotated, said hook member is caused to move axially relative to said rotatable member and move 7 said thrust member,

said rotatable member at one extreme position holding a thrust member operatively connected to said snap acting element and said switch means and responsive to the snap action movement of said snap acting element, i

means operative on said thrust member for selectively positioning said thrust member in such a manner that the snap acting element is permitted to move, is held in one position, and held in the opposite snap position comprising a rotatable member on said casing, 1 t said rotatable member being generally cylindrical and having a helical slot therein,

a hook member having a projection engaging said i ment in one snap position, at its opposed extreme 1 position holding the thrust member and, in turn, the snap acting element in the oppositely snapped position, and in its intermediate position permitting the snap acting element to move to and from its opposed snapped position.

References Cited in the file of this patent UNITED STATES PATENTS 2,281,544 Beeman et a1 MayS, 1942 2,629,791 LeTourneau Feb. 24, 1953 3,042,770

Beeman July 3, 1962 

1. IN A PRESSURE SWITCH, THE COMBINATION COMPRISING A CASING, A RIGID SPRING SUPPORT MEMBER PIVOTED AT ONE END TO SAID CASING ABOUT AN AXIS WITH ITS OTHER END FREE, A BOOSTER SPRING MOUNTED ON SAID SPRING SUPPORT, A SNAP-ACTION LEAF SPRING HAVING THE ENDS THEREOF MOUNTED ON LONGITUDINALLY SPACED POINTS ON SAID BOOSTER SPRING SUCH THAT THE LEAF SPRING IS LONGITUDINALLY COMPRESSED AND BOWED, PRESSURE RESPONSIVE MEANS OPERABLE ON SAID SPRING SUPPORT TO PIVOT SAID SUPPORT, SWITCH MEANS, MEANS OPERATIVELY CONNECTED TO THE LEAF SPRING AND THE SWITCH MEANS AND RESPONSIVE TO THE SNAP ACTION MOVEMENT THEREOF CAUSED BY PIVOTAL MOVEMENT OF SAID SPRING SUPPORT, AND MEANS OPERABLE ON SAID LAST-MENTIONED MEANS FOR SELECTIVELY POSITIONING SAID LAST-MENTIONED MEANS IN SUCH A MANNER THAT THE LEAF SPRING IS PERMITTED TO FLEX, IS HELD IN ONE BOWED POSITION, AND HELD IN THE OPPOSITE BOWED POSITION. 